EP1672253B1 - method for synchronizing a double clutch transmission - Google Patents

Abstract

The method involves associating main shafts to clutches (16, 18). Gears mounted on the shafts cooperate with idle pinions (28, 38) mounted on secondary shafts. Each pinion cooperates with synchronization devices (32, 40) controlled by synchronization actuators. Synchronization rings (34, 42) of the devices and/or clutches that are non-mesh, are implemented to synchronize all the shafts in an impart maximum synchronization duration (Ds). An independent claim is also included for a double clutch transmission device.

Description

The present invention relates to a method and a device for synchronizing the shafts of a gearbox of the double clutch type. This type of box includes two primary shafts that can mate to the engine through two separate clutches. When a gear is engaged, the corresponding clutch engages the output shaft of the engine and the idle gear of the gear ratio engaged is rotated by jaw clutch.

Various devices have been developed to enable the synchronization of the shafts of a gearbox of the double clutch type during a gear change.

A first solution to the problem of synchronizing the shafts in a double-clutch gearbox is to use synchronization rings. When we want to change gear, in particular engage a report requiring a change of primary shaft in gear, it is necessary to come synchronize and then jab the idler gear corresponding to the target ratio. The synchronization in question amounts to equalize the speed of this idle gear and the speed of the secondary shaft by displacement in translation in the direction of the axis of rotation of the secondary shaft of a synchronization ring. This synchronization ring is fixed in rotation with respect to the axis of the secondary shaft. He just rubs on the idler gear to engage in order to speed it up or slow it down as needed.

However, because of their dimensioning, the rings and the actuators are fragile parts. This fragility imposes in particular a maximum force applicable to the synchronization rings by the synchronization actuators. This maximum effort applicable to the synchronization rings does not always make it possible to achieve the synchronization in the given time.

The patent US 5,890,392 discloses a method of synchronizing the shafts of a gearbox type "double clutch" not using synchronization rings. According to this method, during a change of up ratio (under load, that is to say with transmission of a motor torque, or on the road, that is to say without transmission of a driving torque) and descending under load, synchronization is achieved by means of the non-engaged clutch. The clutch initially engaged transmits the entire engine torque. The clutch holding pressure being slightly reduced, it slips very slightly relative to the integral disk of the engine output shaft called flywheel. The closure of the non-engaged clutch intervenes progressively, according to a ramp-shaped instruction. Thus, this clutch progressively transmits a more and more important part of the engine torque. During this time, the clutch initially engaged slips more and more with respect to the flywheel under the effect of an always lower holding pressure. When, finally, the initially non-engaged clutch transmits the entire engine torque, the other clutch is fully open. The clutch initially not engaged can then be engaged without changing the engine torque.

However, this latter method can not be used for a downward gear shift. In fact, in this case, the synchronization consists in accelerating the rotation of the primary shaft corresponding to the non-engaged clutch, in order to cause it to have a speed of rotation which is higher than the rotation speed of the clutch. motor output shaft. To accelerate the primary shaft not in engagement, an additional synchronizing device comprising two friction wheels is then provided in the device described in the patent. US 5,890,392 .

In addition, this method appears unspecific and slow, the accuracy and the response time of a clutch actuator not being of the same nature as those of a synchronization actuator.

The patent DE 199 39 819 discloses a method of synchronizing the shafts of a "double clutch" type gearbox utilizing both the non-engaged clutch and the ring timing device. A maximum duration of synchronization is however not imposed.

The purpose of the device according to the invention is, among other things, to achieve synchronization in the given time, in all cases of figures, in particular without the need for additional device specific to the case of the descent of the gear ratio.

This object of the invention is achieved by means of a method of synchronizing the shafts of a gearbox of the double clutch type, comprising two clutches each associated with a primary shaft. At least one gear is mounted on each of the primary shafts. Each gear can cooperate with a crazy gear, mounted free in translations on at least one secondary shaft. Each of the idle gears can cooperate with a ring synchronization device, each controlled by a synchronization actuator. The synchronization method according to the invention implements one of said synchronization ring devices to synchronize said primary and / or secondary shafts. The method according to the invention is remarkable in that, if the effort required for the synchronization to be carried out in a maximum duration of predetermined synchronization Ds exceeds the maximum effort that the synchronization device can provide, then the non-engaged clutch is also implemented so as to achieve synchronization in the imparted time Ds.

Thus, if the synchronizing ring device is not sufficient to synchronize the shaft to be synchronized in the time provided, the non-engaged clutch is implemented either simultaneously or before the implementation of the ring device. . Synchronization is accelerated.

• calcul du différentiel N_actuel - N_futur entre la vitesse angulaire N_actuel d'un pignon fou à synchroniser et sa vitesse angulaire future N_futur, une fois synchronisé;
• calcul d'un effort F_min minimal à appliquer sur un anneau de synchronisation pour synchroniser ledit pignon fou dans la durée prédéterminée Ds, ledit effort dépendant, entre autres, dudit différentiel N_actuel - N_futur ;
• calcul d'un effort F_max correspondant au plus grand des deux efforts suivant :

• l'effort maximal que peut supporter ledit anneau de synchronisation compte tenu de ses caractéristiques mécaniques ;
• l'effort maximal que peut fournir ledit actionneur de synchronisation ;
• comparaison desdits efforts F_min et F_max ;
• émission, en fonction de ladite comparaison de F_min et F_max :

• d'une consigne de sortie destinée à l'asservissement dudit actionneur de synchronisation si F_min < F_max ;
• d'une consigne de sortie destinée à l'asservissement de l'actionneur dudit embrayage correspondant audit rapport à synchroniser et, éventuellement, d'une consigne de sortie destinée à l'asservissement dudit actionneur de synchronisation si F_min ≥ F_max ;
• retour au début dudit algorithme principal si F_min ≥ F_max .

Preferably, the choice of the synchronization method is performed according to a main algorithm comprising the following steps:

• calculating the _current N differential - N _future between the _current N angular velocity of an idle gear to synchronize and its future _future angular velocity N, once synchronized;
• calculating a minimum force F _min to be applied on a synchronization ring to synchronize said idler gear in the predetermined duration Ds, said effort depending inter alia on said _current N-N _{future differential} ;
• calculating a force F _max corresponding to the largest of the following two forces:

• the maximum force that can support said ring synchronization given its mechanical characteristics;
• the maximum force that can provide said synchronization actuator;
• comparing said forces F _min and F _max ;
• emission, according to said comparison of F _min and F _max :

• an output setpoint for servocontrolling said synchronization actuator if F _min <F _max ;
• an output setpoint for servocontrolling the actuator of said clutch corresponding to said report to be synchronized and, optionally, an output setpoint for servocontrolling said synchronization actuator if F _min ≥ F _max ;
• return to the beginning of said main algorithm if F _min ≥ F _max .

Thus, if the effort required for the synchronization to be performed in the given time is likely to damage the synchronization actuator and / or the synchronization ring, the non-engaged clutch is implemented at the same time that the ring device is before. This reduces the time required for synchronization in this case.

According to a first variant, said _current angular velocity N _of said idle gear is calculated from the measured angular velocity N _primary of the primary shaft corresponding to the gear to engage.

According to a second variant, said _current angular velocity N _of said idle gear is calculated from the _primary angular velocity N of said primary shaft corresponding to said gear to be engaged, calculated from the engine speed.

These two means for determining directly or indirectly the _current angular speed N of the idler gear are easy to implement in a motor vehicle.

According to a first variant, the _future angular velocity N of said synchronized idle gear is calculated from the angular velocity measured N _wheel of the wheels.

According to a second variant, the _future angular velocity N of said synchronized idle gear is measured directly at the level of the at least one secondary shaft.

These two means for determining the _future angular velocity N of the synchronized idle gear are easy to implement in a motor vehicle.

According to a first variant, said effort F _min is precalculated and mapped.

où J représente le moment d'inertie du pignon fou, ϕ̈ la dérivée par rapport au temps de la vitesse angulaire du pignon fou, M_{actionneur_de_synchronisation} le moment de l'effort fourni par l'actionneur de synchronisation et M_résistant le moment de l'effort résistant s'exerçant sur le pignon fou.According to a second variant, said effort F _min is calculated by integrating the fundamental equation of the dynamics governing the movement of said idle gear: $$\ddot{\mathrm{J\phi }}={\mathrm{M}}_{\mathrm{actionneur\_de\_synchronisation}}-{\mathrm{M}}_{\mathrm{resistant}}$$

where J represents the moment of inertia of the idler gear, φ̈ the derivative with respect to the time of the angular speed of the idler gear, M _{actuator_of_synchronization} the moment of the force provided by the synchronizing actuator and M _resisting the moment of the resisting force acting on the idle gear.

These two means for determining the effort F _min are easy to implement in a motor vehicle.

In a first variant, said output setpoint for said synchronization actuator in the case where F _min <F _max is equal to F _min .

Thus, the duration of the synchronization achieved by means of synchronization ring devices is always the same.

In a second variant, said output setpoint for said synchronization actuator in the case where F _min <F _max is between F _min and F _max .

Thus, advantageously, the duration of the synchronization achieved by means of the ring devices can vary and in particular be shortened.

Preferably, when F _min ≥ F _max , said output setpoint for controlling said clutch corresponding to said report to be synchronized is a light-pressing closure setpoint of said clutch.

Thus, the non-engaged clutch is implemented in order to achieve all or part of the synchronization, the ring devices can not perform the synchronization in the time allotted.

In a first variant, said light-weighted closure of said clutch corresponds to a punctual transfer of a torque by said clutch and to its reopening as soon as said torque is transmitted.

In a second variant, said light-weighted closure of said clutch comprises closing said clutch until a given speed value of said idle gear for said algorithm to trigger said synchronization actuator.

Thus, the non-engaged clutch is implemented before the synchronizing ring device in order to achieve a part of the synchronization, ie to bring the idler gear to an angular speed such that the ring device is able to be implemented. The ring device is implemented only when we are sure that it will be able to achieve the synchronization in the given time.

Preferably, the output setpoint for servocontrolling said synchronization actuator is of zero value, when F _min ≥ F _max .

Thus, the ring devices are not implemented until they are able to achieve the synchronization in the given time.

• la figure 1 présente un schéma d'un dispositif conformé pour la mise en oeuvre du procédé selon l'invention ;
• la figure 2 présente un schéma synoptique de l'arbitrage des consignes de synchronisation du rapport à engager selon le procédé selon l'invention.

Other characteristics and advantages of the present invention will result from the examination of the description which follows, presented solely by way of nonlimiting example with reference to the appended figures in which:

• the figure 1 shows a diagram of a device shaped for the implementation of the method according to the invention;
• the figure 2 presents a synoptic diagram of the arbitration of the synchronization instructions of the report to be engaged according to the method according to the invention.

On the figure 1 , the double clutch 10 consists mainly of a flywheel 12 rotated by the output shaft 14 of the motor 15 and two pressure plates 16 and 18 concentric. The plate 16 is fixed to a hub 20. The plate 18 is fixed to the hub 22. In order not to impair the legibility of the diagram, a single gear 24 (respectively 26) is shown on the hub 20 (respectively 22), corresponding each at a speed ratio. The hubs 20 and 22 make the primary shafts of the double clutch 10.

The gear 24 is able to cooperate with the idler gear 28 mounted free to rotate and fixed in translation on the secondary shaft 30. A synchronization device 32 comprising in particular a synchronization ring 34, mounted free in translation and fixed in rotation on the secondary shaft 30 is controlled by a synchronization actuator 36.

Similarly, the gear 26 is able to cooperate with the idler gear wheel mounted to rotate freely and fixed in translation on the secondary shaft. A synchronization device 40 comprising in particular a synchronization ring 42, mounted free in translation and fixed in translation. rotation on the secondary shaft 30, is controlled by a synchronization actuator 36.

On the secondary shaft 30 is mounted an angular speed sensor 44, this secondary shaft driving the wheels 46 and 48 via a differential mechanism 50.

A computer 52 receives signals representative of the angular speed of the secondary shaft 30 and the engine speed and transmits control signals of the synchronization actuators 36 and clutch actuators 54.

When it is desired to change the gear, in particular to engage a gear that requires a change of the input shaft 20, 22, it is necessary to come and synchronize and then engage the idle gear 28, 38 corresponding to the target gear. The synchronization in question amounts to equalize the speed of this idle gear 28, 38 and the speed of the secondary shaft 30.

By means of the device according to the invention, it is possible to use a synchronizing device 32, 40 and / or the non-engaged clutch 16, 18 in order to equalize the speed of the idle gear 28, 38 and the speed of the shaft. secondary 30.

By translation in the direction of the axis of rotation of the secondary shaft 30, translation controlled by the synchronization actuator 36, a synchronization ring 34, 42 rubs on the idler gear 28, 38 to be engaged so as to accelerate or slow down, as needed.

However, the clutch 16, 18 not engaged can also be implemented. A lightly pressing closure of this clutch 16, 18 makes it possible to transmit a portion of the engine torque and thus accelerate or slow down the primary shaft corresponding to the gear ratio to be engaged.

The calculator 52 is connected, as shown in FIG. figure 1 , to an angular speed sensor 44 of the secondary shaft 30 and to a motor speed sensor thereby enabling it to obtain signals representative of the angular speed of the secondary shaft, N _secondary , and the engine speed, N _motor

où r représente le rapport entre la vitesse de rotation de l'arbre primaire 20, 22, N_primaire, et la vitesse de rotation N_actuel du pignon fou 28, 38 considéré. Ce rapport r est une valeur fixée par la mécanique.From the quantities and information available to the computer 52 (gear ratio engaged, gear to engage), the method, in a first step calculates the _current angular speed N of idle gear 28, 38 to synchronize and its future speed N _future , once synchronized using the equations: $$\begin{array}{l}{\mathrm{NOT}}_{\mathrm{actual}}\mathrm{=}{\mathrm{NOT}}_{\mathrm{engine}}\mathrm{\times }\mathrm{r}\\ {\mathrm{NOT}}_{\mathrm{future}}\mathrm{=}{\mathrm{NOT}}_{\mathrm{secondary}}\end{array}$$

where r represents the ratio between the rotational speed of the primary shaft 20, 22, _primary N, and N _current rotational speed of the idler gear 28, 38 considered. This ratio r is a value fixed by the mechanics.

These quantities can also be calculated from other quantities measured. For example, the _current rotation speed N of the idle gear 28, 38 considered can be calculated from the measurement of the _primary angular velocity N of the primary shaft 20, 22 concerned: $$\begin{array}{c}{\mathrm{NOT}}_{\mathrm{actual}}\mathrm{=}{\mathrm{NOT}}_{\mathrm{primair}}\mathrm{\times }\mathrm{r}\end{array}$$

où r_pont est le rapport de pont, c'est-à-dire le rapport entre la vitesse de rotation N_roue des roues 46, 48 et la vitesse de rotation N_secondaire de l'arbre secondaire 30. Le rapport de pont est donc une donnée mécanique.Likewise, the _future angular velocity N of the idle gear 28, 38 once synchronized can be calculated from the measurement of the angular velocity N _wheel of the wheels 46, 48 by means of the equation: $${\mathrm{NOT}}_{\mathrm{future}}\mathrm{=}\frac{{\mathrm{NOT}}_{\mathrm{wheel}}}{{\mathrm{r}}_{\mathrm{bridge}}}$$

where r _bridge is the _bridge ratio, that is to say the ratio between the _wheel rotation speed N _wheel 46, 48 and the _secondary rotation speed N of the secondary shaft 30. The bridge ratio is therefore a mechanical data.

Having thus calculated the _current angular velocity N of an idle gear 28, 38 to be synchronized and its future _future angular velocity N _, once synchronized, it is possible to calculate the _current differential N - N _future

In a second step of the method, two efforts are calculated.

First, the minimum force F _min to be applied to the synchronization ring 34, 42 is calculated to synchronize in a predetermined time, fixed, for example, according to driving pleasure considerations. This effort depends on the ratio to be engaged, the predetermined timing and the differential N _current - N _future calculated previously. This effort can be calculated beforehand in the design office and entered in the form of cartography in the calculator.

où J représente le moment d'inertie du pignon fou, ϕ̈ la dérivée par rapport au temps de la vitesse angulaire du pignon fou 28, 38, M_{actionneur_de_synchronisation} le moment de l'effort fourni par l'actionneur de synchronisation 36 et M_résistant le moment de l'effort résistant s'exerçant sur le pignon fou. Ce moment de l'effort résistant M_résistant dépend du rapport de vitesse initialement engagé, du rapport de vitesse à engager et du différentiel N_actuel - N_futur. Ce moment peut être calculé préalablement en bureau d'étude et rentré sous forme de cartographie dans le calculateur.It could also be calculated in real time by the calculator by integrating the fundamental equation of dynamics governing the movement of the idler gear: $$\mathrm{J}\ddot{\mathrm{\phi }}={\mathrm{M}}_{\mathrm{actionneur\_de\_synchronisation}}\mathrm{-}{\mathrm{M}}_{\mathrm{resistant}}$$

where J represents the moment of inertia of the idler gear, φ̈ the derivative with respect to the time of the angular speed of the idle gear 28, 38, M _{actuator_of_synchronization} the moment of the force supplied by the synchronizing actuator 36 and M _resisting the moment of the resisting force exerted on the crazy gear. This moment of _resistance M resistant strain depends on the gear ratio initially engaged, the speed ratio and engaging the differential _current N - N _future. This moment can be calculated beforehand in the office of study and returned in the form of cartography in the calculator.

• l'effort maximal que peut supporter l'anneau de synchronisation 34, 42 compte tenu de ses caractéristiques mécaniques, à savoir, entre autres, la matériau dont il est composé et les préconisations provenant des concepteurs de l'anneau comme, par exemple, la pression maximale supportée par l'anneau.
• l'effort maximal que peut fournir l'actionneur de synchronisation 36.

A force F _max corresponding to the smaller of the following two efforts is then calculated:

• the maximum force that can support the synchronization ring 34, 42 given its mechanical characteristics, namely, among others, the material of which it is composed and the recommendations from the designers of the ring as, for example, the maximum pressure supported by the ring.
• the maximum force that can be provided by the synchronization actuator 36.

The effort F _max therefore depends, inter alia, on the synchronization ring concerned and therefore on the speed ratio concerned, the _current N-N _future speed differential, and the desired synchronization time since, for a _current N speed difference. - N _future data, the shorter the desired synchronization time, the greater the effort to provide the ring 34, 42 by the synchronization actuator 36 is large. This effort F _max can be mapped in particular according to these parameters.

In a third step, the forces F _min and F _max calculated previously are compared.

If F _min <F _max , the effort required to synchronize the idle gear 28, 38 in the desired time is less than the effort acceptable by the synchronization ring 34, 42 and the effort that can provide the actuator synchronization 36 to the ring 34, 42. In this case, the synchronization actuator 36 is capable of achieving synchronization within the allotted time. The output of the algorithm is then a control setpoint of the synchronization actuator 36 concerned. This setpoint may for example be equal to F _min , which makes it possible to achieve the synchronization in the given time.

It could however take a value between F _min and F _max , knowing that, the greater the effort applied, the faster the synchronization, to the detriment of the life of the synchronization ring 34, 42 and / or the synchronization actuator 36 (manufacturer's compromise).

If F _min ≥ F _max , the effort required to synchronize the idle gear 28, 38 in the desired time is greater than the acceptable effort by the ring 34, 42 synchronization or the effort that can provide the actuator synchronization 36 to the ring. In this case, the synchronization actuator 36 is not able, alone, to perform the synchronization in the given time. The algorithm then delivers an output setpoint for the actuator of the clutch 54 not in engagement. This setpoint is a "light-weight closing" instruction of this clutch 16, that is to say that clutch 16, 18 corresponding to the gear engaged is slightly closed.

According to a first variant, this light support closure may, for example, consist of closing the clutch 16, 18 in order to obtain the transfer of a predetermined torque and the reopening of the clutch as soon as this torque is transmitted.

According to a second variant, it could consist of a slight clutch closure of the clutch until the rotational speed of the primary shaft 20, 22 has reached a predetermined threshold value, allowing the synchronization ring device 32, 40 to achieve synchronization within the specified time. Of course, these embodiments of light support closure are presented by way of non-limiting examples.

In the case where F _min ≥ F _max, then the algorithm restarts at the first stage (determination of current angular velocities and future _current N and N _future of the idler gear 28, 38) where the current angular velocity of the idler N _current s is closer to the future speed of the idler gear N _future under the action of the clutch 16, 18 not in gear.

The figure 2 presents a synoptic diagram of the arbitration of the synchronization instructions of the report to be engaged according to the method according to the invention.

Of course, the present invention is not limited to the embodiment described, provides by way of indicative example, not limiting. Indeed, such a method also applies to a motor vehicle or not having more than one gear per primary shaft, that is to say more than one ratio per primary shaft. In particular, if each primary shaft comprises two gear ratios, the secondary shaft comprises four idle gears. However, only two ring synchronization devices are necessary in the case where each device is able to cooperate with two idle gears. In this case, the implementation of the method according to the invention does not require additional equipment compared to the case presented above.

Such a method also applies to a motor vehicle or not having more than one secondary axis, an angular speed sensor by secondary shaft then being necessary.

Claims (14)

1. Method for synchronizing the shafts (20, 22, 30) of a transmission (10) of the double clutch type, comprising two clutches (16, 18) each one associated with a primary shaft (20, 22), at least one gear (24, 26) being mounted on each of the primary shafts (20, 22) and being able to collaborate with an idler pinion (28, 38) mounted free in terms of translational movement on at least one secondary shaft (30), each of the idler pinions (28, 38) being able to collaborate with a synchro rings (32, 40) device in which each ring is controlled via a synchro actuator (36) using one of the said synchro ring devices (32, 40) to synchronize the said primary (20, 22) and/or secondary (30) shafts, characterized in that if the force needed to achieve synchronization within a predetermined maximum synchronizing time Ds exceeds the maximum force that the synchro device can provide, then the clutch (16, 18) not engaged is also used in order to achieve synchronization within the given time Ds.
2. Method according to Claim 1, characterized in that the choice of synchronization method is made according to a main algorithm involving the following steps:

   - calculating the differential N_current - N_future between the angular velocity N_current of an idler pinion (28, 38) that is to be synchronized and the future angular velocity N_future it will have once sychronized;

   - calculating a minimum force F_min to be applied to a synchro ring (34, 42) in order to synchronize the said idler pinion (28, 38) within the predetermined time Ds, the said force being dependent, amongst other things, on the said differential N_current - N_future;

   - calculating a force F_max that corresponds to the greater of the following two forces:

   - the maximum force that the said synchro ring (34, 42) can withstand given its mechanical properties;

   - the maximum force that the said synchro actuator (36) can supply;

   - comparing the said forces F_min and F_max;

   - transmitting, on the basis of the said comparison between F_min and F_max :

   - an output datum value intended to control the said sychro actuator (36) if F_min < F_max;

   - an output datum value intended to control the actuator (54) of the said clutch (16, 18) corresponding to the said gear ratio that is to be synchronized and, possibly an output datum valve intended to control the said synchro actuator (36) if F_min ≥ F_max ;

   - returning to the start of the said main algorithm if F_min ≥ F_max
3. Method according to Claim 2, characterized in that the said angular velocity N_current of the said idler pinion (28, 38) is calculated from the measured angular velocity N_primary of the primary shaft (20, 22) corresponding to the gear ratio that is to be engaged.
4. Method according to Claim 3, characterized in that the said angular velocity N_current of the said idler pinion (28, 38) is calculated from the angular velocity N_primary of the said primary shaft (20, 22) corresponding to the said gear ratio that is to be engaged, calculated from the engine speed.
5. Method according to one of Claims 2 to 4, characterized in that the angular velocity N_future of the said synchronized idler pinion (28, 38) is calculated from the measured angular velocity N_wheel of the wheels (46, 48).
6. Method according to one of Claims 2 to 4, characterized in that the angular velocity N_future of the said synchronized idler pinion (28, 38) is measured directly at the at least one secondary shaft (30).
7. Method according to one of Claims 2 to 6, characterized in that the said force F_min is precalculated and mapped.
8. Method according to any one of Claims 2 to 6, characterized in that the said force F_min is calculated by integrating the fundamental dynamic equation governing the movement of the said idler pinion (28, 38) : $$\mathrm{J}\ddot{\mathrm{\varphi }}={\mathrm{M}}_{\mathrm{synchro\_actuator}}\mathrm{-}{\mathrm{M}}_{\mathrm{resistive}}$$

   

   
   where J represents the moment of inertia of the idler pinion, ϕ̈ represents the derivative with respect to time of the angular velocity of the idler pinion (28, 38), M_{synchro- actuator} represents the moment of the force supplied by the synchro actuator (36) and M_resistive represents the moment of the resistive force exerted on the idler pinion.
9. Method according to any of Claims 2 to 8, characterized in that said output datum value intended for the said synchro actuator (36) when F_min < F_max is equal to F_min.
10. Method according to any of Claims 2 to 8, characterized in that the said output datum value intended for the said synchro actuator (36) when F_min < F_max ranges between F_min and F_max.
11. Method according to one of Claims 2 to 10, characterized in that when F_min ≥ F_max, the said output datum value intended to operate the said clutch (16, 18) corresponding to the said gear ratio that is to be synchronized is a datum value to let the said clutch (16, 18) in just beyond the kiss point.
12. Method according to Claim 11, characterized in that letting the said clutch (16, 18) in just beyond the kiss point corresponds to a brief transfer of torque through the said clutch (16, 18) which is then let out again as soon as the said torque has been transmitted.
13. Method according to Claim 11, characterized in that letting the said clutch (16, 18) in just beyond the kiss point consists in letting the said clutch (16, 18) in until the said idler pinion (28, 38) reaches a determined speed value that will allow the said algorithm to deploy the said synchro actuator (36).
14. Method according to one of Claims 11 to 13, characterized in that the output datum value intended to control the said synchro actuator (36) is of zero value.

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